跆拳道教练计划:研究发现低盐饮食效果不佳，招致异议四起。

The study is published in the May 4 issue of The Journal of the American Medical Association. It involved only those without high blood pressure at the start, was observational, considered at best suggestive and not conclusive. It included 3,681 middle-aged Europeans who did not have high blood pressure or cardiovascular disease and followed them for an average of 7.9 years. 

        这项研究在《美国医学协会杂志》5月4号期刊上发表。由于研究涉及的对象只是观察那些起初没有高血压的人，因此被认为最多也就是有点提示作用，并不具有结论性。该研究对象为3681名中年欧洲人，他们都未曾患有高血压或者心血管疾病，并且跟踪调查平均时间为7.9年。

The researchers assessed the participants’ sodium consumption at the study’s start and at its conclusion by measuring the amount of sodium excreted in urine over a 24-hour period.  All the sodium that is consumed is excreted in urine within a day, so this method is the most precise way to determine sodium consumption. 

        研究人员在研究开始时评测了志愿者的钠摄入，又通过测算志愿者24小时时间段尿液中钠的含量得出结论。所有摄入的盐份都在一天之内随着尿液排出了，因此这个方法是鉴定盐摄入最准确的方法。

The investigators found that the less salt people ate, the more likely they were to die of heart disease — 50 people in the lowest third of salt consumption (2.5 grams of sodium per day) died during the study as compared with 24 in the medium group (3.9 grams of sodium per day) and 10 in the highest salt consumption group (6.0 grams of sodium per day).  And while those eating the most salt had, on average, a slight increase in systolic blood pressure — a 1.71-millimeter increase in pressure for each 2.5-gram increase in sodium per day — they were no more likely to develop hypertension. 

        调查人员发现盐摄入越少的人，死于心脏病的几率就越高——盐摄入最少的第三组（每天2.5克）有50人在研究中死亡，第二组（每天3.9克）有24人死亡，而盐摄入最多的那组（每天6克）有10人死亡。就平均水平来看，盐摄入最多的那组人，虽然收缩压稍微有所增加——每天的盐摄入增加2.5克，血压也增加1.71毫米——而他们却不会得高血压。

“If the goal is to prevent hypertension” with lower sodium consumption, said the lead author, Dr. Jan A. Staessen, a professor of medicine at the University of Leuven, in Belgium, “this study shows it does not work.”

        减少钠的摄入”若是为了预防高血压的话“，主笔兼比利时鲁汶大学医学教授简A.斯泰森博士说道，”这项研究则说明这根本就不管用。“

But among the study’s other problems, Dr. Briss said, its subjects who seemed to consume the smallest amount of sodium also provided less urine than those consuming more, an indication that they might not have collected all of their urine in an 24-hour period. 

        布里斯博士说：”但是在该研究的其他问题之中，似乎盐摄入最少的那组人，其尿液也比盐摄入更多的人排出得更少，这说明他们可能没有收集到他们24小时时间段内所有的尿液。

Dr. Frank Sacks of the Harvard School of Public Health agreed and also said the study was flawed. 

        哈佛公共卫生学院的弗兰克塞克斯博士同意此观点，并也表示该研究存在漏洞。

“It’s a problematic study,” Dr. Sacks said. “We shouldn’t be guiding any kind of public health decisions on it.” 

        "这项研究是有问题的，“塞克斯博士说,”我们不应对此作任何引导公共卫生的决定。”

Dr. Michael Alderman, a blood pressure researcher at Albert Einstein College of Medicine and editor of the American Journal of Hypertension, said medical literature on salt and health effects was inconsistent. But, Dr. Alderman said, the new study is not the only one to find adverse effects of low-sodium diets. His own study, with people who had high blood pressure, found that those who ate the least salt were most likely to die. 

        爱因斯坦医学院的一位血压研究人员兼《美国高血压症杂志》编辑迈克尔埃德尔曼博士称有关盐和健康效果的医学文献是前后矛盾的。但是发现低盐饮食的副作用并非是该新研究的首创。他个人对患有高血压人群的研究就曾发现盐摄入最少的人死亡的概率也最高。

Dr. Alderman said that he once was an unpaid consultant for the Salt Institute but that he now did no consulting for it or for the food industry and did not receive any support or take any money from industry groups. 

        埃德尔曼博士说他曾经无偿地为美国食盐协会当过顾问，但是现在已经没有再担任了，也没有给其他粮食产业做过顾问，并且没有接受过任何援助也没有收取过产业集团的钱。

Lowering salt consumption, Dr. Alderman said, has consequences beyond blood pressure. It also, for example, increases insulin resistance, which can increase the risk of heart disease.

        减少盐的摄入，埃德尔曼说，除了血压之外还会有其他的影响。例如，它会增加胰岛素抵抗，而胰岛素抵抗会增加心脏病的风险。

“Diet is a complicated business,” he said. “There are going to be unintended consequences.” 

        他说：“饮食是门复杂的学问，总会出现意想不到的影响效果。”

One problem with the salt debates, Dr. Alderman said, is that all the studies are inadequate. Either they are short-term intervention studies in which people are given huge amounts of salt and then deprived of salt to see effects on blood pressure or they are studies, like this one, that observe populations and ask if those who happen to consume less salt are healthier. 

        食盐的各种争论存在一个问题，埃德尔曼博士说，就是所有的调查研究其实都是不完善的。要么是短期的介入性研究，给研究对象食用大量的食盐后，然后把盐分离出来并观测盐对血压的影响，要么就是，如同这次的研究，通过观察人数并询问盐摄入越少的人是否越健康。

“Observational studies tell you what people will experience if they select a diet,” Dr. Alderman said. “They do not tell you what will happen if you change peoples’ sodium intake.” 

        “如果研究对象选择了一种饮食方式，观察性研究就会告知你你的研究对象会有怎样的经历，”埃德尔曼博士说，"如果改变了研究对象的盐摄入，那么你就不会从中得知将会发生什么。”

What is needed, Dr. Alderman said, is a large study in which people are randomly assigned to follow a low-sodium diet or not and followed for years to see if eating less salt improves health and reduces the death rate from cardiovascular disease. 

        埃德尔曼博士说现在所需的就是一项庞大的研究，研究对象要随机被分配遵守低盐摄入饮食或否，并且跟踪调查几年时间，观察是否低盐摄入会改善健康状况以及是否降低由心血管疾病导致的死亡概率。

But that study, others say, will never happen. 

        但是其他人则说那项研究永远不会出现。

“This is one of those really interesting situations,” said Dr. Lawrence Appel, a professor of medicine, epidemiology and international health at Johns Hopkins Medical Institutions. “You can say, ‘O.K., let’s dismiss the observational studies because they have all these problems.’ ” But, he said, despite the virtues of a randomized controlled clinical trial, such a study “will never ever be done.” It would be impossible to keep people on a low-sodium diet for years with so much sodium added to prepared foods. 

        “这和那些情形一样，真的很有趣，”约翰斯霍普金斯医学研究所流行病学和国际卫生学院医学教授劳伦斯阿佩尔博士说，“你会说，‘好吧，让我们忽略掉观察性研究吧，因为这些毛病它们都具备了。’” 但是他说，除了要对随机控制的临床试验表示一下赞赏外，这样的研究“永远永远也完成不了。” 要让研究对象长年遵循低盐饮食，又要给预制食物添加那么多盐，这不可能。

Dr. Briss adds that it would not be prudent to defer public health actions while researchers wait for results of a clinical trial that might not even be feasible. 

        布里斯博士补充说：”当研究人员都在等候一次或许甚至都不太行得通的临床试验的结果时，拖延公共健康大行动可不明智!"

Dr. Alderman disagrees.

        埃德尔曼博士对此表示异议。

“The low-salt advocates suggest that all 300 million Americans be subjected to a low-salt diet. But if they can’t get people on a low-salt diet for a clinical trial, what are they talking about?” 

        “低盐倡导者们建议全美3亿人都加入到低盐饮食中来。可若是他们都不能让人们进行有关低盐饮食的临床试验，那还论什么论？”

He added: “It will cost money, but that’s why we do science. It will also cost money to change the composition of food.”

        他补充说道："这需要钱，但这也正是我们搞科学的原因。而且改变食物成分也得花钱。”